1. Field of the Invention
This invention relates to lidar remote sensing systems.
2. Background information
Lidar remote sensing systems using conical scan patterns are known. Because of the angular lag between the transmitted beam and the return beam, the scan must be very slow or the system must be a "stop and stare" system. In the stop and stare system, the laser beam is transmitted and the scan is stopped until the return beam from the target arrives. This limits scanning speed and requires a relatively complex mechanical design in order to counter the force exerted by the scanner non-continuous motion and to absorb the resultant vibration.
If the scan is continuous, it must be very slow or the return beam will not travel along the optical path of the transmitted beam. The amount of deviation of the return beam from the optical path will depend primarily on the rate of the scan and the distance to the target of the transmitted beam. Because of the fact that the return beam does not follow the optical path, the power loss in the returned signal is significant. It would be desirable to have a scanning lidar remote sensing system in which the returned radiation travels along the optical path followed by the transmitted beam.